package main

import (
	"fmt"
	"os"
)

func exists(filename string) bool {
	f, err := os.Open(filename)
	if err != nil {
		return false
	}
	f.Close()
	return true
}

func readFile(filename string) ([]byte, error) {
	f, err := os.Open(filename)
	if err != nil {
		return nil, err
	}
	fi, err := f.Stat()
	if err != nil {
		return nil, err
	}
	buf := make([]byte, fi.Size())
	n, err := f.Read(buf)
	if err != nil {
		return nil, err
	}
	if n != len(buf) {
		return nil, fmt.Errorf("Unexpected file size: %d vs %d", n, len(buf))
	}
	return buf, nil
}